One manner of increasing passenger space in an airplane is to increase the length of the fuselage. This process is commonly known as "stretching". Typical problems associated with "stretching" an airplane and ultimately limiting the size of the airplane are: (1) limitation of aft-body rotational clearance, (2) disproportionate growth of the lower lobe cargo space, and (3) maneuverability of the airplane around the airport. These problems occur in principle with single as well as double deck airplanes. For singledeck airplanes they become critical at a lesser increment of growth then for double deck airplanes. The Boeing 747 airplanes have an upper deck in the forward portion of the fuselage. The Stratocruiser has a lower lobe lounge. The McDonald-Douglas MD11 aircraft has a lower lobe seating option. There have been numerous large flying boats with multiple decks. Usually a double deck configuration is chosen to improve interior efficiency, sometimes utilizing space that was initially provided for other reasons. For example, the upper deck in the Boeing 747 airplanes, was the result of requiring a nose cargo door configuration. Flying boats have unique hull requirements, limiting length and therefore favoring multi-deck arrangements.
Increasing passenger space by use of an additional deck is preferred to merely increasing the length or overall size of the aircraft because it results in a shorter aircraft which is easier to maneuver around an airport. A partial upper deck is preferred because it provides a beneficial ratio of lower lobe cargo space to passenger seat space. Prior experience with the addition of an upper deck to an airplane has provided Mach number and drag penalties. However, heretofore, all upper deck additions have been either a forward partial upper deck or a full upper deck. In the making of the present invention, it was discovered that a partial upper deck in the aft region of the fuselage both provided the desired additional passenger space and reduced drag. The unique body geometry of airplanes embodying the present invention results in an increase in critical Mach number on a Wing of given sweep and thickness. This discovery allows that for a desired critical Mach number a wing can be designed to have less sweep, greater thickness, or a combination of both. The airplane of the present invention is a single deck airplane with an upper deck addition to the aft portion of the fuselage. This design proved to allow growth beyond that which is possible with a conventional stretch aircraft, without experiencing the Mach number drag penalties experienced with a full upper deck or a forward partial upper deck.